The system used in some countries is simple, and it solves the fare collection personnel issue (“How to make all Green Line riders pay their fare,’’ Editorial, June 3). Roving random conductors or transit police check tickets and issue large fines to evaders — large enough to be a serious deterrent and to cover the cost of fare evasion elsewhere.

This would require some technological change. The system I experienced used paper tickets that were stamped on the train, with train and time information, but there’s no obvious reason a Charlie Card couldn’t contain the same information — such as location and time of last use — and be readable with a handheld device.

We would still have some fare evaders zipping out one door as the conductor came in the other, or trying to play the odds, but the fines should make up the difference if they are several hundred times the ticket price.

The added official presence would also be good for security on the trains.

Andrea Haber

Framingham